CN112359420A

CN112359420A - Method for growing tungsten disulfide single crystal on surface of liquid gold substrate

Info

Publication number: CN112359420A
Application number: CN202011428845.2A
Authority: CN
Inventors: 兰飞飞; 张嵩; 董增印; 王再恩; 王健; 李佳起; 杨丹丹; 张颖; 李强
Original assignee: CETC 46 Research Institute
Current assignee: CETC 46 Research Institute
Priority date: 2020-12-09
Filing date: 2020-12-09
Publication date: 2021-02-12

Abstract

The invention discloses a method for growing tungsten disulfide single crystals on the surface of a liquid gold substrate. The method comprises the following steps: placing tungsten trioxide powder in a quartz boat, placing a gold substrate on the surface of a sapphire substrate, placing the gold substrate in a quartz groove, placing a quartz tube in a system for vacuumizing, heating the system to reach a growth temperature, heating sulfur powder, introducing sulfur steam into the system, and starting WS₂And (4) growing a single crystal. Tungsten trioxide is used as a raw material, sulfur vapor is utilized to carry out sulfuration on the tungsten trioxide at high temperature to grow tungsten sulfide, gold foil is used as a substrate in the growth process, the gold substrate is heated to 1050 ℃, the melting point of the gold substrate is 1040 ℃, the surface of the gold foil is melted to be in a liquid state near the melting point of gold, grain boundaries on the surface of polycrystalline gold disappear in the state, the surface state of the substrate is consistent, and WS is uniform in height₂When the substrate is grown, the crystal orientations of different nucleation points can be kept consistent, and finally the WS with consistent crystal orientations₂The single crystals are combined and grown to obtain large-size single crystals.

Description

Method for growing tungsten disulfide single crystal on surface of liquid gold substrate

Technical Field

The invention relates to a method for preparing WS by adopting a CVD method₂A single crystal process, in particular to a tungsten disulfide (WS) on the surface of a liquid gold substrate_2）A method for growing a single crystal.

Background

Two-dimensional WS₂Is a typical representative of transition metal sulfides, is a typical two-dimensional layered material, a single layer of WS₂The mobility of the direct band gap semiconductor material exceeds 1000cm²The V & s is far higher than the mobility of the silicon material under the same thickness; WS₂The surface has no dangling bond, so that good stability can be maintained in a complex environment; WS₂The base field effect transistor has ultra-low crystalline state power consumption, and the application of the base field effect transistor can remarkably reduce the system power consumption. Furthermore, WS₂Has excellent optical performance and good mechanical flexibility. For this purpose, WS₂Has potential application prospect in the fields of micro-electronics, flexible photoelectrons and the like.

WS has been obtained by researchers at present on wafer level using CVD₂A single-layer continuous film is obtained by merging and growing single crystals which are spontaneously nucleated at different positions, and the spontaneously nucleated single crystals have different crystal orientations, so that a large number of grain boundaries exist in the continuous film, the grain boundaries are defect-enriched positions, the quality of the film is seriously reduced, and the WS is seriously reduced₂The mobility of the material. Therefore, large domain size WS is achieved₂Study of growth of Single Crystal is WS₂The problem that must be solved in the research process. WS currently prepared by CVD₂The size of the crystal domain is only tens of micrometers, and it is difficult to obtain a large sizeWS of size₂And (3) single crystal.

WS by current CVD method₂Tungsten trioxide is mainly used as a W source in the growth process of the single crystal, high-purity sulfur powder is used as a sulfur source, sulfur vapor heated under certain growth conditions reaches a tungsten trioxide source area along with the transportation of carrier gas, and the sulfur vapor reacts with the tungsten trioxide to obtain the degraded tungsten-containing oxide. Due to the substrate and WS₂There is no bonding between them, therefore WS₂The spontaneous nucleation process is performed on the surface of the substrate, the crystal orientations of different nucleation points are difficult to control, and finally the WS obtained after merging growth is caused₂Has a large amount of grain boundaries in the medium, and is difficult to obtain large-size WS₂And (3) single crystal.

Disclosure of Invention

The invention aims to solve the problem of growing WS by the existing CVD method₂The problem of undersize of single crystal, especially providing a liquid gold substrate surface WS₂Method for growing single crystal to achieve increase of WS₂Increase in single crystal size of WS₂The purpose of the quality of the single crystal.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: liquid gold substrate surface WS₂Single crystal growth method, characterized in that WS is carried out on the surface of a liquid gold substrate₂Growing a single crystal, wherein the crystal growing process is completed according to the following steps:

in the first step, tungsten trioxide powder is placed in a quartz boat, and the growth surface of the substrate is placed on the quartz boat with the growth surface facing downward.

Secondly, placing a gold substrate on the surface of the sapphire substrate, then placing the sapphire in a quartz groove, and placing a quartz tube in a CVD growth system; and (3) vacuumizing the CVD growth system, and introducing Ar gas for purging when the pressure in the system is 0mbar, wherein the flow of the Ar gas is 500 sccm.

And thirdly, reducing the flow rate of Ar to 100sccm-150sccm, and keeping the pressure in the system at 10mbar-20 mbar.

And fourthly, heating the system to 1050 ℃, starting to heat the sulfur powder after the temperature of the system is increased to reach the growth temperature for 5min, and controlling the heating temperature to 190-250 ℃.

Fifthly, the temperature of the sulfur powder reaches the set temperatureAfter the degree is reached, sulfur steam is introduced into the system, and WS is started to be carried out₂And (3) growing the single crystal for 20-50 min.

And sixthly, cooling and sampling after growth is finished.

Preparation of WS according to the invention₂Mechanism of single crystal: heating the gold substrate to the temperature near the melting point in the CVD growth system, and melting the surface of the gold substrate into liquid gold, wherein the surface state of the liquid gold substrate is highly consistent. WS in this state₂The crystal orientations at different nucleation points are consistent, so WS at different nucleation points₂Continuous WS obtained after merged growth of single crystals₂The film becomes a large size WS without grain boundary₂And (3) single crystal. Thereby realizing large size WS₂And (4) growing a single crystal.

Tungsten trioxide is used as a raw material, sulfur vapor is utilized to carry out sulfuration on the tungsten trioxide at high temperature to grow tungsten sulfide, gold foil is used as a substrate in the growth process, the gold substrate is heated to 1050 ℃, the melting point of the gold substrate is 1040 ℃, the surface of the gold foil is melted to be in a liquid state near the melting point of gold, grain boundaries on the surface of polycrystalline gold disappear in the state, the surface state of the substrate is consistent, and WS is uniform in height₂When the substrate is grown, the crystal orientations of different nucleation points can be kept consistent, and finally the WS with consistent crystal orientations₂The single crystals are combined and grown to obtain large-size single crystals.

The invention has the beneficial effects that: the method carries out WS on the surface of liquid gold₂By utilizing the height consistency of the surface of the liquid gold substrate, WS at different nucleation points is enabled to grow by multi-point nucleation₂The crystal orientations are the same, and finally, the WS2 single crystal with large size is obtained after combination and growth. The application of the method can realize large-size WS₂Controlled growth of single crystals.

Drawings

FIG. 1 is a schematic view of a device for growing a liquid metal substrate surface according to the present invention.

Detailed Description

The invention is further illustrated by the following figures and examples.

Example (b):

in a first step, as shown in FIG. 1, 0.06g of high purity tungsten trioxide powder 1 is placed in one end of a quartz boat 2 opened at both ends and grooved, and a gold substrate 3 attached to the surface of a sapphire substrate is placed in a groove at the other end of the quartz boat 2.

And secondly, placing the growth device into a CVD growth system, charging, vacuumizing the system, and introducing Ar gas for purging when the pressure in the system is 0mbar, wherein the flow rate of the Ar gas is 500 sccm.

And thirdly, reducing the flow rate of Ar to 100sccm, keeping the pressure in the system at 10mbar, and heating the system to 1050 ℃.

And fourthly, after the temperature in the system reaches the set temperature, keeping the temperature for 5min, and then starting heating the sulfur powder, wherein the heating temperature is 190 ℃.

Fifthly, when the temperature of the sulfur powder reaches the set temperature, introducing sulfur steam into the system, and starting WS₂And (4) growing the single crystal for 30 min.

And sixthly, naturally cooling to room temperature after the growth is finished, and taking out a sample for testing. Discovery of WS by differential interference microscopy₂The size of the single crystal triangle can reach centimeter magnitude.

Claims

1. A method for growing tungsten disulfide single crystal on the surface of a liquid gold substrate is characterized in that WS is carried out on the surface of the liquid gold substrate₂Growing a single crystal, wherein the crystal growing process is completed according to the following steps:

firstly, tungsten trioxide powder is placed in a quartz boat, and a substrate growth surface is placed on the quartz boat downwards;

secondly, placing a gold substrate on the surface of the sapphire substrate, then placing the sapphire in a quartz groove, and placing a quartz tube in a CVD growth system; vacuumizing the CVD growth system, and introducing Ar gas for purging when the pressure in the system is 0mbar, wherein the flow rate of the Ar gas is 500 sccm;

thirdly, reducing the flow rate of Ar to 100sccm-150sccm, and keeping the pressure in the system at 10mbar-20 mbar;

fourthly, heating the system to 1050 ℃, starting to heat the sulfur powder after the temperature of the system is increased to reach the growth temperature for 5min, and controlling the heating temperature to 190-250 ℃;

fifthly, after the temperature of the sulfur powder reaches the set temperature, introducing sulfur steam into the system, and starting WS₂Growing the single crystal for 20-50 min;

and sixthly, cooling and sampling after growth is finished.